Ionic serve to start on specific IP

Just update you CLI

dev server running: http://localhost:8100/

to make your ip adress to work in VPS

Follow this steps
Install the Ionic CLI

The easiest way to get the Ionic CLI is through npm.

$ npm install -g ionic

Note: For a global install of -g ionic, OSX/Linux users may need to prefix the command with sudo.
Update Ionic lib

Update Ionic library files, which are found in the www/lib/ionic directory. If bower is being used by the project, this command will automatically run bower update ionic, otherwise this command updates the local static files from Ionic’s CDN.

$ ionic lib update